PubMed · 15551973
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Samuel S Wexler. 2004. Practical information.. https://doi.org/10.14219/jada.archive.2004.0034
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With a plethora of post systems available, it is often difficult to decide which one to use. This is made more difficult by the fact that new posts are introduced before existing ones are fully evaluated in laboratory and clinical studies. This paper therefore describes the different post types and the main advantages and disadvantages of each. In addition, the choice of post system will influence whether further tooth preparation is required and will dictate which luting cement and core material are most appropriate. Whilst the choice of post will, for many dentists, be driven by personal preference and a history of clinical success, there are certain pit falls to avoid and these are outlined.
The aim of this study was to determine the effect of ultrasonic vibration on the force necessary to remove pre-fabricated and anatomic and cast posts. Two hundred and forty teeth were divided into two groups. In group I, a 0.8-mm metallic pre-fabricated post, Unimetric-Maillefer, was utilized; in group II, cast copper-aluminum alloy posts measuring 0.8, 1.0 and 1.2 mm in diameter were used. The root canals were prepared in three different diameters: 0.8, 1.0 and 1.2 mm, with a length of 10 mm. The posts were cemented with glass ionomer cement resulting in 20 specimens for each subgroup. Half of the sample was submitted to ultrasonic vibration for 3 min, while the other half did not receive any vibration. The specimens were submitted to traction in a universal testing machine. The results were analyzed by non-parametric Mann-Whitney U, Wilcoxon and Kruskal-Wallis tests. The application of ultrasonic vibration significantly reduced the retention provided by the glass ionomer cement in the fixation of intracanal posts. The ultrasonic action was effective in both pre-fabricated and anatomic and cast posts. The effectiveness of the ultrasonic vibration was not related to the cementation line or the diameter of the post.
This study evaluated the hypothesis that if hydrophilic nanofillers were dispersed evenly within the adhesive layer under moist conditions, adding them to a one-bottle dentin adhesive might improve the mechanical properties of the adhesive layer, and accordingly increase the bond strength. The flexural strength (FS), the degree of conversion (DC), and the microtensile bond strength (MTBS) to the dentin of four experimental ethanol-based one-bottle dentin adhesives containing 0, 0.5, 1.0, and 3.0 wt % of 12-nm hydrophilic fumed silica were evaluated, and the distribution of the nanofillers were compared using transmission electron microscopy (TEM). Although the nanofiller content did not affect the DC, the FS tended to increase with increasing nanofiller content. The MTBS appeared to increase when up to 1.0 wt % of the nanofillers were added, but they were statistically not significant. However, when 3.0 wt % of the nanofillers were added, the MTBS decreased significantly comparing to the adhesive containing 0.5 wt % nanofillers (p < 0.05). The TEM image suggested that if the nanofillers within the adhesive were 3.0 wt % and applied to a wet dentin surface, they aggregated easily into large clusters and would decrease the MTBS.